Electrical machine.



6w 0 9 1 1 1 G E D D B T N E T A P H M M A L m R ELECTRICAL MACHINE.

APPLICATION FILED FEB.21,1906.

WITNESSES: f

UNITED STATES PAEENT OFFICE.

BENJAMIN G. L AM'ME, OF PI'I'TSBURG,- PENNSYLVANIA, ASSIGNOR TOWESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A COR- .roRArIoN orPENNSYLVANIA.

ELECTRICAL MACHINE.

Patented Dec. 11,1906.

v Application 615a February 21,1905. Serial No. 246,684.

chines, of which the following is a specifica- .tion.

My invention relates to electrical machines, and particularly tomachines which embody high-resistance connections between theirarmature-coils and their commutator-bars or between difierent portionsof their windings.

The object of my invention is to provide a machine of the characterindicated in which the high-resistance conductors -are so disposed as toinsure certain advantagesnot secured by the structures and arrangementswhich have heretofore been employed.

-Patent No. 758,668; granted to the West 7 inghouse Electric &Manufacturing v Company May 3, 1904, upon an application-filed y -me,discloses a construction in which hi h-resistance leads between thearmaturecoils and the commutator-bars'of an elec-- t'rical machine arelocated in the bottoms of the slots which contain the armature-windingsand are connected to the armature-coils at'the' ends remote from thecommutator,

Patent No.- 780,047, granted January 17,

1 .1905, to the Westinghouse Electric & Manufacturing Company upon anapplication filed by me, shows a construction slmilar to that of thepatent just mentioned and differs from what-is set forth in the earlierpatent in the provision of a plurality of lengths ofresistance-conductor instead ofa single length in order to secure thedesired amount of resistance and also in case the resistance-conductoris doubled once upon itself in the elimination of inductive effects.Each of theinventions covered by y the above-mentioned patentsconstituted a distinct and practical advance in the'art; but eachpossessed the 'dis'advan tagethatthe resistance-leads must beaccommodated Withinthe armature-slots, and

therefore the slots must be made considerably dee er than would beotherwise required, t ereby'malgin'g'the proportions of armature teeth.and" slots sometimes undesirable for the best/working"conditions.Furthermore; the-location of the resistance-leads Eac in close proximityto the armature-coils involved the transfer of some of the heatgenerated in such leads to the coils, and thereby reduced the efficiencyof the latter. I

In order to avoid enlargement of the coreslots beyond what is demandedfor proper electrical proportions and to also avoid transference of heatfrom the resistance-leads in the armature-coils, I propose to provideinresistance-leads and to double each of such leads once upon itself,thus rendering it noninductive.

Figure' 1 0f the accompanying drawings a longitudinal section ofone-half. of an'armature embodying my invention, a portion of the shaftbeing broken away. Fig. 2 is a face view-of approximately a quadrant ofone of the laminae of the armature-core shown in Fig. 1,-and Figs. 3 and4 are similar views of modified formsof laminzc that may be employed inarmatures embodying my invention.

The laminated core 1 of the armature is provided with ventilating passaes 2 and is mounted upon a spider 3, whic in turn is suitably securedupon a shaft 4, these parts having any form, dimensions, and arrangeforany tor-cylin er 5 may also be of any usual or approved construction andmay have its bars properly connected to the armature-coils 6 y means ofhigh-resistance leads 7. The

coils 6 are located and disposed in open, partially open, or closedslots Sin the core 1 and adjacent to its surface, and theresistanceleads 7 may be connected to the commutator ends of the coils-6by means of suitable connectors 9 and eachdoubled once upon itself andconnected at its other end directly to the pro er commutator-bar of thecylinder 5. doubled; lead 7 is placed in a slot 1-0, which is located atany convenient distance from the outer surface of the core, and theseslots are preferably disposed uniformly around the armature-axis,Inasmuch as theseslots are not open to the surface of the armature excet at their ends, they may be made of suchs ape, dimensions, and numberas will cause the least disturbance of the mag neticand electricalcircuitsof the armature.

dependent slots in the armature-core for the ment that may be usual inthe art or desired particular service. The commuta- Since there isordinarily more available space .for sheet-steel beneath the coil-slotsthan is actually required for magnetic purposes, the cutting away ofenough material to accommodate the resistance-leads does not interferewith the proper operationof the machine. Furthermore, the dispositionofthe resistance-leads herein set forth possesses several distinctadvantages. For example, to with this arrangement the resistance-leadsare embedded in the interior of the core, and the heat generated in theleads is therefore transmitted to the core-laminae and disseminated moreeffectively than would be the 5 case if the leads were otherwiselocated.

The slots for the leads may be of such form as is best adapted fortransferrin the heat, and the number of leads in each s ot m-a beanything desired irrespective of the num er,

size,, or 'shape of the armature-slots at the surface-that is to say,the slots for the ar mature-coils may be of such. sha e and dimensionsas may be re uired for t e best operating conditions of t earmature-Winding,

2 5 While the slots for the resistance-leads ma be of such other formand dimensions as wi 1 best facilitate the performance of the functionsof such resistance-leads V Figs. 2, 3, and 4 illustrate some of thevarious forms that the armature-laminae may assume in practice, theresistance-conductor slots being greater in number than the armaj'ture-coil slots in Fi 2, the same in number in Fig. 3, and smal er innumber in Fig. 4. 3 5 In orderthat the resistance-conductors may bedistributed to best advantage among the slots provided for theirreception, it is desirable that the number of slots in the inner setbear some definite relation to the number at the outer periphery, andsuch a relation may be the inverse of the ratio of the number ofconductors in the resistance-lead slots to the number in thearmature-coil slots. With the arrangement show'nin Fig. 2 it may beassumed that each of the slots in the. inner set will accommodate eightresistance-leads, and each of the slots at the outer periphery 1 willaccommodate ten armature-conductors;

and therefore the numbers 'of slots in the two sets may be in the ratioof one hundredv and twenty to ninety-six, as here shown. With thestructure shown in Fig. 3 it is intended that each slot shall containthesamehumber ofconductors and with the structure shown 5 5 in Fig. 4that the ratio of the number of conductors in each slot of the inner setto those in each slot of the outer set shall be as eight to six, thenumbers of slots in the two sets in the latter case being ninety-sixand-seventytwo, respectively.

Another advantage incident to this construction is that theresistance-leads may be removed, if desired, without interference withthe armature-coils. 5 While I. have shown and described my -in ventionas ap lied to a rotatable armature having its coi s connectedvtocommutatorbars, I have not restricted the structure to I use in either amotor or a generator to the eX- clusion of the other service, sincewhile the '70 invention is especially usefulin connection withsingle-phase alternating-current motors, yet there maybe instances whereit will be found useful in connection-with genera tors, and-I desire itto be further understood 7' 5 that the invention is notnecessarilylimited to machines of the commutator t e, since the arrangement ofresistance lea s or conductors which is here shown and" described may beutilized and beeffective wherever resistances are used in connectionwith machine-windingsas,- for example, in the case of induction-motors,in which resistances are connected in circuit-with either rotatable orstationary secondary windings. In such relations the resistances may beembedded in their own slots in the core of the secondary member of themotor and the number and size of such slots ma be made entirelyindependent of the num er and size of the slots adjacent to the surfaceof the core which contain the main secondary conductors:

The dimensions, location, and arrangement of parts may be varied Withincomparatively Wide limits from what I have shown, and I therefore desireit to be understood that m invention is to be construed as free from allimitations exceptsuch as may be imposed bythe prior art. I

I claim as my invention 1. A core of an electrical machine havin one setof slots adjacent to its surface and another set of slots more'remotefrom such surface, and conductors located in said slots, the numbers ofconductors per slot being in inverse ratio to the numbers of slots inthe corresponding sets.

2. A core of an electrical machine havin one set of slots adjacent toits surface and another set of slots more remote from such no surface,and conductors located in'said slots, the number of conductors perslot'bearing a" definite relation to the ratlo of the numbers 'of slotsper set.

3. In an electrical machine, a core having two concentric sets of slotsand two sets of conductors located in said slots and connected together,the number in the inner set bearing a definite relation to the number inthe outer set.

4. In an electrical machine, a core having two concentric sets of slotsand two sets of conductors located in said slots and connect 1 edtogether, the numbers of conductors per' slot being in inverse ratio tothe numbers of 1 2 5 slots er set.

5. ii an electrical "machine, a core having two concentric sets ofslots, a set of lowre-- sistance conductors in the outer slots and a setof high-resistance conductors in the inner I 0 slots, said sets ofconductors being connected ing in inverse ratio to the numbers of slotstogether and the numbers of conductors per per set. v

slotbeing in inverse ratio to the numbers of In testimony whereof I havehereunto subslots per set. scribed my name this 18th day of February,

5 6. In an electrical machine, a core having 1905. i

an outer set of open slots and an inner set comprising a greater numberof closed slots and sets of conductors of relatively low and -Witnesses:

high resistance in the slots of the respective M. M. NAGLE, 10 sets, thenumbers of conductors per slot be- BIRNEY HINES.

BENJ. e. LAMME.

